Energy is often defined as the capacity to do work. Several different forms of energy, such as kinetic, potential, thermal, electromagnetic, chemical, and nuclear energy have been defined to explain all known natural phenomena.
Kinetic energy is the energy of vertical or horizontal motion. Any object which is affected by vibration, rotation or translation is said to have kinetic energy. Vibration creates vibrational energy, rotation creates rotational energy and translation (moving from one location to another) creates translational energy.
An objects kinetic energy is the energy that it has due to its motion. The work that is needed to move an object from a stop to full movement is gained during acceleration and the energy is maintained unless it changes speed. It also means that the same amount of opposite work is required to make it stop accelerating as starting to accelerate.
We all see examples of kinetic energy when we view space launches, which although they require chemical energy to take off, they gain kinetic energy as they reach their maximum velocity. The energy that is gained during the launch remains constant while the spacecraft is in orbit and at re-entry the kinetic energy becomes heat.
It is possible to transfer kinetic energy, for instance when playing pool, kinetic energy is provided to the cue ball when it is struck with a pool stick. When the cue ball hits another ball, it slows down and the ball it hits then gains speed, preserving kinetic energy.
Roller coasters are also rich in kinetic energy, the cars reach maximum kinetic energy when they are at the bottom of the roller coaster and as they rise, and the kinetic energy is converted to gravitational energy. Kinetic energy is the additional energy that is built up due to the acceleration of the roller coaster.
Energy that is stored in a system that can be released for other forms of energy (such as kinetic energy) is known as potential energy. The name is derived from the fact that the object in the system changes as the energy is released.
Potential energy is created when a force that pulls something backwards towards its original position (such as a spring). The more formal definition of potential energy is the energy of position, or the energy an object has to have due to its position in space.
(A catapult for example is a good example of elastic potential energy)
Potential energy sources are numerous since they are associated with individual kinds of force for instance, elastic potential energy, nuclear potential energy, chemical potential energy, or thermal energy which generally has two components, potential energy and kinetic energy.
Thermal Energy is the system of energy that increases with temperature. That is the energy content of a system is changed by an increase (or decrease) in the temperature of the system. The term thermal energy is not widely used, since it is counter-intuitive. Heat can typically only be defined as a spontaneous flow of energy between two objects caused by the temperature differences between those two objects. Thermal energy may be converted to chemical energy through the use of blast furnaces, to electromagnetic radiation energy through the use of hot objects, mechanical energy by the use of steam turbines and through thermal energy through the use of heat exchangers. Thermal energy may also be converted to electrical energy through the use of thermo-couplings.
Objects with temperatures above absolute 0 (-273 degrees Celsius) emit electromagnetic energy. This energy is released in waves which are absorbed by another surface. Common sources of electromagnetic radiation are radio waves, microwaves, ultraviolet radiation, X-rays and gamma rays. Electromagnetic waves as a general phenomenon were predicted by the classical laws of electricity and magnetism, known as Maxwell’s equations.
A common laboratory spectroscope can detect wavelengths from 2 nm to 2500 nm.
Legend:
γ = Gamma rays
HX = Hard X-rays
SX = Soft X-Rays
EUV = Extreme ultraviolet
NUV = Near ultraviolet
Visible light
NIR = Near infrared
MIR = Moderate infrared
FIR = Far infrared
Radio waves:
EHF = Extremely high frequency (Microwaves)
SHF = Super high frequency (Microwaves)
UHF = Ultrahigh frequency
VHF = Very high frequency
HF = High frequency
MF = Medium frequency
LF = Low frequency
VLF = Very low frequency
VF = Voice frequency
ELF = Extremely low frequency
Work done by changing electric charges, electrons and protons (the process of aggregation), chemical energy is the result of a system increasing energy and the results are converted to other types of energy. Chemical energy is converted to mechanical energy in the body through the muscles, through fire it is converted to thermal energy, through fuel cells it is converted to electrical energy and through chemical reactions, it remains chemical energy. The greatest source of energy that is used by mankind, we find chemical energy at work in everything from a simple match to an airplane. Most of the electricity in that we use is produced from chemical energy produced in the burning of oil, gas and coal. Since the industrial age, chemical energy use continues to be a driving force with the social and environmental affects continuing to drive controversy on the effects of how we use and manage energy consumption.
Automobiles convert chemical energy into mechanical energy and through digestion; our bodies turn chemical energy into fuel for us to carry on our day to day activities. The ability to convert chemical energy first to mechanical energy then to electrical energy is how we are able to have power plants.
Nuclear energy is defined as any energy that is derived from the nucleus of a source of energy. Nuclear energy was first discovered accidentally by French physicist Henri Becquerel in 1896, when he found that photographic plates stored in the dark near uranium were blackened like X-ray plates, which had been just recently been discovered.
Nuclear energy is released by three chemical change processes:
* Radioactive decay, where a proton or neutron in the radioactive nucleus decays spontaneously by emitting a particle
* Fusion, two atomic nuclei fuse together to form a heavier nucleus
* Fission, the breaking of heavy nucleus into two nuclei
In 2007, the International Atomic Energy Agency (IAEA) reported 439 nuclear power reactors operating in 31 countries around the world. The US produces the most nuclear energy; nearly 80% of all electricity consumed is from nuclear reactors. In Europe, 30% of the electricity that is consumed is from nuclear reactors. Military ships typically use nuclear marine propulsion systems. Research continues to overcome some of the safety issues that surround nuclear energy.
Nuclear safety covers:
- The research and testing of the possible incidents/events at a nuclear power plant,
- What equipment and actions are designed to prevent those incidents/events from having serious consequences,
- The calculation of the probabilities of multiple systems and/or actions failing thus allowing serious consequences,
- The evaluation of the worst-possible timing and scope of those serious consequences (the worst-possible in extreme cases being a release of radiation),
- The actions taken to protect the public during a release of radiation,
- The training and rehearsals performed to ensure readiness in case an incident/event occurs.
Many different safety features have been added to nuclear power plants and in the United States, the NRC has responsible over nuclear safety.
With ongoing discussions constantly, we are growing more and more concerned about what our energy consumption is doing to the environment. As a result, we are consistently seeking more information about alternative energy sources and new and more environmentally friendly technologies are being investigated.
Some of these alternative energy sources are natural gas, solar, hydroelectric, wind, biomass, green energy, wave and tidal energy. The term alternative is used to contrast with fossil fuels according to some sources, and some sources may use it interchangeably with renewable energy.
Natural Gas is major source of electricity, which utilizes gas turbines as well as steam turbines and offers high efficiency when used with a gas and steam turbine combination. Burning much cleaner than other fossil fuels (such as coal or oil) natural gas produces approximately 30% less carbon dioxide than petroleum and about 45% less than coal. Natural gas is used wherever it can be obtained at a reasonable cost. Since it is a non-renewable source of energy, it is estimated that the supply of natural gas could be depleted as early as 2085.
Perhaps the best source of rewable energy (and the most utilized) is solar energy which gains its energy from the sun. The sun supports all life on earth through heat and light and allows us to use solar based resources such as wind and wave power. Solar power is used synonymously with solar energy or more specifically to refer to the conversion of sunlight into electricity.
In a variety of industries, solar energy is harnessed and used to help production. For instance, greenhouses carefully control the use of solar heat and light to grow specialty crops; architects often use solar designs which may provide lighting, comfortable temperatures, and improved air quality by tailoring building orientation, proportion, window placement, and material components to the local climate and environment; solar water heating systems are occasionally used commercially (Israel is the leading user of solar hot water – more than 90% of their residential buildings use it), and China is also a world leader in solar hot water use; solar thermal technologies can provide process heat for drying food and clothes, driving high temperature chemical reactions and melting metals; solar cookers use sunlight for cooking, drying and pasteurization and help offset fuel costs, by reducing demand for fuel or firewood, which helps improve air quality.
Electricity that is produced with hydro power is termed hydroelectricity and currently accounts for more than 63% of all renewable energy worldwide. Large hydroelectric power stations are not common; however China which has more than 50% of the world’s hydroelectric capacity has several small hydroelectric plants. Use of hydroelectricity is not without environmental impact however since it requires water being dammed and utilized to generate power which can cause a disruption in the ecosystem.
In high supply, renewable, clean and widely distributed, wind energy can be used to replace fossil fuel derived electricity. Since wind power is typically only used to supply about 10% of electric demand, there are currently not any problems that can’t be addressed. Because of other challenges which have yet to be solved, wind probably will not be widely used to serve a greater demand for some time.
There have been a number of recent developments of mini-windmills which could be adapted to home use, including:
- The AeroTecture vertical-axis turbine
- The AeroVironment Architectural Wind Project
- The piezoelectric windmill project
- The Swift home wind turbine. The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative
- The Motorwave micro-wind turbine
Consumer guides are available to help potential customers learn about residential-scale wind systems, three of which are:
- “Small Wind Electric Systems: A U.S. Consumer’s Guide” by the Dept. of Energy’s Wind Powering America program
- “Wind Turbine Buyer’s Guide” From Home Power Magazine
- “Apples & Oranges 2002: Choosing a Home-Sized Wind Generator”
Much more information is also available at the American Wind Energy Association’s web site at:
- http://www.awea.org/smallwind
- FAQ: http://www.awea.org/smallwind/faq.html
- www.awea.org/smallwind/toolbox2/index.html
Wind power can be a controversial issue, and several main areas of dispute are debated between supporters and opponents including growth and cost trends, scalability, potential, feasibility, economics, ecology, impact on wildlife, noise, safety and aesthetics. As well as many instances of environmental opposition to wind power including: (taken from wikipedia.org)
# a wind farm that was proposed several miles off the coast of Cape Cod, environmentalists raised objections. Ted Kennedy, who had previously always been a supporter of wind power, objected to the proposal, because he owns a summer home at Cape Cod.
# On October 16, 2003 in Galway, Ireland, construction of the foundation of a wind farm caused almost half a square kilometer of bog to slide 2.5 kilometers down a hillside. The slide destroyed an unoccupied farmhouse and blocked two roads. Nearby residents expressed concern over these environmental impacts.
# On December 4, 2007, environmentalists filed lawsuits to block two proposed wind farms in southern Texas. The lawsuits expressed concerns over wetlands, habitat, endangered species and migratory birds.
# On January 12, 2004, it was reported that the Center for Biological Diversity filed a lawsuit against wind farm owners for killing tens of thousands of birds at the Altamont Pass Wind Resource Area near San Francisco, California.
# On December 7, 2007, it was reported that environmentalists opposed a plan to build a wind farm in western Maryland. Ajax Eastman, whom the article described as “a conservationist from Baltimore whose opposition has helped stall construction of other wind farms in western Maryland,” was quoted as saying, “The idea of destroying the Appalachian ridge tops for such a little bit of energy capacity doesn’t make any sense to me.” Paulette Hammond, president of the Maryland Conservation Council, was quoted as saying, “This would denude some very valuable forest tree canopy … and wouldn’t provide nearly the amount of energy we’ll need.” The article also said, “Dan Boone, a former state wildlife biologist who has been fighting wind farms in western Maryland, said that the Savage River and Potomac state forests contain rare old-growth trees and that threatened species that shouldn’t be disturbed.”
Biomass energy is created from recently living organisms (such as plants, animal and by-products). Manure, garden waste, crop residues may all be sources of biomass energy. A renewable energy source, it is carbon based and some products are grown specifically for the purposes of producing biomass energy including corn, soybeans, rapeseed, sugar beets, and sugar cane. Many biodegradable materials such as hemp, straw, manure, rice husks and food waste can contribute to biomass fuel sources, and not only do they make a good alternative energy source, they help control waste.
The most common biomass fuels are vegetable oil which can be used for food or fuel, biodiesel (common in Europe), bioalcohols (commonly ethanol, propanol, and butanol) though they are not currently widely used.
Green power can refer specifically to electricity generated from “green” sources including anaerobic digestion, geothermal power, wind power, small-scale hydropower, solar power, biomass power, tidal power and wave power as well as power derived from waste incineration.
Some common carriers of electricity offer the consumer the ability to purchase green electricity through their providers. Often, the customer pays a slightly higher price for this ability, however it has been discovered that you may not necessarily be receiving power that is generated from a green energy source, since utility companies buy their electricity from sources who might be generating fossil fuel, nuclear or renewable energy sources, etc., therefore less than 5% of the overall amount of electricity available is considered to be from ‘green’ sources.
In the United States, we have some providers that are recognized as ‘green power providers’ including: Constellation NewEnergy; 3Degrees; Sterling Planet; SunEdison; Pacific Power and Rocky Mountain Power; and Silicon Valley Power. The combined green power provided by those six sources equals more than 5 billion kilowatt-hours per year, which is enough to power nearly 465,000 average U.S. households.
The EPA recognized the West Division of Macy’s Inc., the Timberland Company, and the City of Chico, California, for their on-site generation of solar power, and also recognized New York University and six companies for purchasing green power. The EPA also named the City of Bellingham, Washington, and six more companies as their Green Power Partners of the Year. Among all the companies, PepsiCo stands out as a partner of the year, because three of its bottling companies were also honored for buying green power. In addition, CRS awarded its Market Development Awards to the Western Washington Green Power Campaign, Clif Bar, and two individuals: John Schaeffer and Bill Spratley.
Throughout the country, more than half of all U.S. electricity customers now have an option to purchase some type of green power product from a retail electricity provider. Roughly one-quarter of the nation’s utilities offer green power programs to customers, and voluntary retail sales of renewable energy in the United States totaled more than 12 billion kilowatt-hours in 2006, a 40% increase over the previous year. (Taken from wikipedia.org)
Wave power, a rewable energy source, is defined as the ability to capture energy from the oceans surface waves for electricity generation, desalination and water pumping, Wave power is not developed enough for their to be any commercially available wave farms in development, though on December 18, 2007, Pacific Gas and Electric Company announced its support for plans to build America’s first commercial wave power plant off the coast of Northern California. The plant will operate with buoys placed 2.5 miles offshore and is expected to generate a maximum of 2 megawatts of electricity allowing the farm to generate enough power to supply approximately 1500 homes.
Some of the challenges with the implementation of wave power decides include (a) efficiency in converting wave motions into electricity; (b) developing units that can withstand storm damage and corrosion (from salt), and the overall cost of conversion which includes mooring systems, installation & maintenance costs and delivery costs.
Use of energy is something that most of us take for granted, whether it’s the power to run a light bulb in our home, cook a meal, refrigerate perishable food items, drive our cars, or even run our computers.
As time progresses and alternative methods of delivering energy to our homes becomes more efficient, we can anticipate seeing more environmentally friendly energy sources, however we can expect the cost of these sources to be more than we currently pay today for our energy.
New cars, busses, trolleys continue to lead the trend in use of alternative (and renewable) energy sources; though the increased cost to purchase continues to discourage the wide-spread purchase of these vehicles. Many homes are being built with solar panels for heating though most of these homes continue to have typical heating systems as backup.
Types of Energy 
